In recent years, resinous molded articles have become popular as cylindrical molded articles such as pipes and the like, in view of easy processing, weight reduction and cost-reduction. However, the resin generally has a low heat resistance, and thus metallic molded articles are mostly used in fields which require heat resistance. For example, in a vehicle, a radiator-pipe connecting a radiator to an engine is often made of metal. In such a field, a heat-resistant resin is require, because of weight saving and inexpensive production.
To respond to these requirements, a multi-layer pipe which comprises polyphenylene sulfide (PPS) resin or a modified aromatic polyphenylene sulfide-derived resin is disclosed in Japanese Unexamined Patent Application, Publication No. H11-300844 (Patent Document 1), which is used in a vehicle. Also, a multi-layer pipe is disclosed in Japanese Unexamined Patent Application, Publication No. 2003-21275 (Patent Document 2), in which a property such as adhesion between layers in the multi-layer pipe of patent document 1 is improved.
[Patent Document 1] Japanese Unexamined Patent Application, Publication No. H11-300844
[Patent Document 2] Japanese Unexamined Patent Application, Publication No. 2003-21275